The Archaeology of Food and Cooking

A Nutty Blog with A-Corny Title: Acorns and the Human Diet

As the chilly autumnal breezes cause leaves and other flora to “fall,” my attention is brought to those little oaky morsels beloved by squirrels and interior decorators alike: acorns.

This past weekend I had a table at Michigan Archaeology Day at the Michigan History Center. My display was called “Ancient Michigan Meals” and I displayed the various kinds of foods that were present in the archaeological remains at the Cloudman site, including squash, wild rice, maize, and fish. Many adults and children alike were surprised by the acorns also on display. Several kids expressed bewilderment at why people ate what they called “squirrel food”. But these nuts are much more than rodent fodder.

Acorns have been important components of human diet in many regions of the world for millennia. They have been found in large quantities at many archaeological sites across Eastern North America, Mexico, Europe/Mediterranean, and Asia (1). Beginning ca. 3000 BC, many societies in California developed an acorn economy, where acorns become a staple food (2). Many of these societies continued to rely heavily on acorns until the arrival of Europeans. Some have posited that the Natufians, precursors to world’s very first farmers in the Levant, may have also been reliant on acorns, allowing them to become sedentary, or settle in one spot permanently, before developing agriculture (3).

However, having an acorn-heavy diet is no simple task. Unlike other nuts, you cannot just pick them up off the ground and eat them. Well, you could, but you would likely regret it. Acorns contain tannins, organic compounds found a variety of foods, including berries, nuts, legumes, coffee, tea, and wine. Tannins taste bitter and can cause gastrointestinal problems when eaten in large quantities. Acorns contain a LOT of tannins, so to make them edible, they must first be leached.

There are several methods for leaching acorns. Boiling is common leaching method, one that seems to have been preferred by historic-era Ojibwe and Huron. The Ojibwe sometimes boiled acorns whole and then ate them (4), but usually boiled them several times over and then ground them into flour (5). The Huron boiled them in wood ash to neutralize the tannins (6). Most often the acorns were then ground into flour and added to soups as a thickening agent.

Another method for leaching is to essentially wash the tannins out of the acorns. Traditionally, this involves securing a bag of acorns to a fixed spot along a river or stream, which will wash out the tannins over the course of a day or two.

I found out first hand just how labor-intensive simply shelling acorns can be. Barb Barton, a wild foods expert, has been gathering and eating acorns for years, and she recently let me help her process some. The images below depict the shelling process:

Breaking up the shells in Barb’s nut cracking contraption

After cracking the shells, you must complete the shelling by hand, when you encounter some rotten interiors and the occasional worm

Beautiful, nutritious acorn nutmeats, ready to be leached

Barb replicates the “river” leaching method by putting chopped acorns in a mesh basket at the top of a bucket with a nozzle at the bottom, which she places in the sink with the faucet just barely running for a day or so. The constant, if slow, flow of water eventually leaches the tannins. The acorns bits are then roasted dry and ground into flour.

Acorns take a lot of work. So why were they so popular in the past? If you’ve ever walked through any park with oak trees in late September/early October, you will have seen the massive amounts of acorns that drop from the trees at this time. This means that they would be relatively easy to collect in large quantities, so, as my friend Dr. Kate Frederick points out, that initial labor investment would be low. In places like northern Michigan, acorns could be stored as an emergency food, and accessed in the lean times of later winter/early spring if necessary, when the labor of food preparation would be more than worth it (7).

But acorns were not just emergency food in the Upper Great Lakes and were eaten frequently as an important source of fats and carbohydrates (8, 9). They were frequently cooked in the pottery vessels at the Cloudman site throughout its 1500-year history, demonstrating that the original residents of Michigan were simply nuts about acorns.*

*Note: the phrase “Nuts About Acorns” was shamelessly stolen from the great wise Sean Dunham. Find his paper and dissertation and give them a read!

Having done reproduction cookery (as I’ve mentioned before), I’m always astonished at the sheer amount of labor involved. Using a reproduction Viking quern, it took quite a bit of time and effort to produce small amounts of low quality flour. We tried bolting the flour once, and gave up on that idea because that further reduced our output. (Between 3/4 and 7/8 of the flour was filtered out, leaving only a small amount of higher quality flour.) No wonder white bread was seen as a status symbol for millennia! (Which lead directly to the crap white bread that infests the mega marts down to this day.)

And it’s not just flour… Washing and peeling vegetables, grinding spices, etc… etc… All took considerable effort.

It’s not electricity that I miss the most in reproduction cookery. It’s having vegetables already washed, and/or frozen veggies. Flour already ground and bagged. Spices pre-ground and handy in my cabinet. A lot of folks like to gripe about how various labor saving devices and products have altered our diet for the worse (and they’re not entirely wrong)… But as with white bread, they generally don’t realize these things did *not* evolve in a vacuum.

Which also leads back to the point you made about why acorns were so popular… As much work as they took to process, they took much less effort to gather and were much less perishable. Humans have been trying to maximize caloric availability v. effort for a very long time.

I’m always fascinated to think about how much of one’s day was once devoted to food procurement and preparation. Since we live in a modern capitalist economy and no longer devote our days to subsistence-related activities (besides those in the food industry), I think it’s easy to forget just how long it takes to process food from start to finish. Restaurants and groceries stores sure help speed up the process!